Many studies for treating and preventing diabetes have been conducted worldwide up to now, but the prevalence rate of diabetes has been steadily increased. Recently, the obesity population has been rapidly increased. The diabetes population is also expected to be rapidly increased due to inadequate life habits and aging.
The diabetes were roughly divided into insulin-dependent diabetes melitus and insulin-independent diabetes mellitus, but are now changed into Type 1 diabetes melitus and Type 2 diabetes melitus, respectively. It is known that Type 2 diabetes melitus occupying 90% or more diabetes patients is caused by dysfunction of insulin (resistance to insulin) or secreting defect of insulin. For its treatment, oral hypoglycemic agent or insulin formulation is used with diet and exercise.
Representative oral hypoglycemic agents are sulfonylurea promoting the secretion of insulin, metformin improving the resistance to insulin, glytazone, alpha glycosidase inhibitor inhibiting the absorption of glucose, etc.
Oral hypoglycemic agents having three kinds of pharmacological mechanisms are used in clinical trial, but their uses are restricted due to adverse effects such as hypoglycemia, toxicity of liver, weight increase, lacticacidemia, etc. Also, it is known that blood glucose can be controlled up to certain degree by actively using oral hypoglycemic agent or insulin formulation. However, two clinical test results recently completed on a large scale [The Diabetes Control and Complications Trial (DCCT) groups: Eng J Med, 2002, 342:381, The United Kingdom Prospective Diabets Study (UKPDS) groups: JAMA, 2002, 287:2542] are very negative thereto.
Despite active treatment of diabetes, a significant number of diabetes patients failed to attain the standard blood glucose level. Recently, medicines mixing and formulating medicines having different pharmacological mechanisms are in market from the conclusion that a medicine having one pharmacological mechanism has a limit to decrease the blood glucose to the normal level.
To successfully treat Type 2 diabetes mellitus having more complex pathogenesis than Type 1 diabetes mellitus, the development of a medicine having two or three pharmacological mechanisms, not one mechanism, has been required. In this point of view, it has been required to develop agents for preventing and treating diabetes from natural substances having various ingredients.
With rapidly increasing the obesity population, many people who do not show the characteristic symptoms of diabetes fail in the glucose tolerance test. These people are called as people showing impaired glucose tolerance (IGT), and it is known that a significant number of people among those showing IGT suffer from diabetes eventually. Therefore, the development of formulation which can block or delay the progress of diabetes in those people showing IGT is as important as early discovery of those showing IGT.
Blood glucose can be controlled by feedback of glucose, i.e., glucose absorbed to the human body is burnt at the peripheral tissue, or glucose stimulates beta cells to release insulin. In this regard, the ability capable of normally metabolizing glucose in the living body is called as glucose tolerance. Hyperglycemia may be caused by decrease of glucose tolerance.
In particular, ginseng among medicinal plants shows various physiological activities. Antidiabetic activity of ginseng was reported by many researchers, and Sotaniemi et al. and Vuksan, et al. (Sotaniemi et al., Diabetes Care, 1995, 18:1373, Vuksan et al., Arch Intern Med, 2000, 60:1009, Vuksan et al., Diabetes Care, 2000, 23:1221) reported the clinical test result about antidiabetic activity of Panax quinquefolius, and the animal test result about antidiabetic activity of Panax ginseng or Panax quinquefolius. However, as Vuksan et al. recently reported, even ginseng marketed by same company may show different antidiabetic activities experiment by experiment [Variable effects of American ginseng: a batch of American ginseng (Panax quinquefolius L.) with a depressed ginsenoside profile does not affect postprandial glycemia: Eur J Clin Nutr, 2003, 57(2):243-8].
These differences are because each ginseng has different amount or constitution of saponin, and it is not clearly known which ginsenoside of saponin has antidiabetic activity.
Thus, the present inventors have repeated antidiabetic tests in aged experiment animals, and conducted the glucose tolerance tests by using a composition consisting of a small amount of ginsenosides in red ginseng or ginseng, and then discovered that a mixture of ginsenosides Rg3, Rg5 and Rk1 shows superior blood glucose control effect to each ginsenoside, thereby completing the present invention.